High-intensity air-cooled electric lamp assembly



.Aug'. 9, 1966 R. w. PORTER 3,265,385

HIGH-INTENSITY AIR-COOLED ELECTRIC LAMFKASSEMBLY Filed Feb. 13, 1964INVENTOR- United States Patent V O 3,265,885 HIGH-INTENSITY AIR-COOLEDELECTRIC LAMP ASSEMBLY Robert W. Borter, Campbell, Calif., assiguor toMetro- Kalvar, 'Inc., Culver City, Calif., a corporation of DelawareFiled Feb. 13, 1964, Ser. No. 344,633

Claims. (Cl. 240-47) This invention relates to high-intensity lamps andis particularly directed to an air-cooled lamp assembly employing ahigh-pressure mercury vapor lamp. Such a device finds particularusefulness in connection with photographic printing of motion picturefilm, but this is by way of example and not of limitation.

High-intensity electric lamps of the type employing high-pressuremercury vapor have heretofore required liquid cooling in order todissipate the intense heat generated by the lamp, but the passage of theliquid coolant around the lamp has required that the usable light passthrough the coolant stream, thereby reducing the light intensity.

It is a principal object of the present invention to provide anair-cooled or gas-cooled high-intensity lamp assembly so that theintensity of light developed by the lamp is not materially reduced inpassing through the stream of air or gas which acts as the coolant.

Another object is to provide a novel form of air-cooled lamp house foruse with abigh-intensity electric lamp employing a straight transparenttube or envelope containing high-pressure mercury vapor.

Other andmore detailed objects and advantages will appear hereinafter.

In the drawings:

FIGURE 1 is a perspective view showing a preferred embodiment of thisinvention.

FIGURE 2 is a sectional elevation taken substantially on the lines 22 asshown in FIGURE 1.

FIGURE 3 is a transverse sectional elevation taken substantially on thelines 3-3 as shown in FIGURE 2.

FIGURE 4 is a longitudinal sectional view partially broken away showinga modification.

Referring to the drawings, the housing is formed of aluminum alloy orother material having a good thermal conductivity and is provided with alarge number of integral cooling fins 11. A cavity 12 in the housingextends axially for the full length thereof. This cavity is bounded by areflector surface 13, havinga cross-section shape such as, for example,an ellipse proportioned to cause light to be emitted from the cavity 12in a predetermined pattern. The lamp 14 is placed at a focal point ofthe ellipse, and preferably comprises a high-pressure mercury arc lamp.Lamps of this type may be obtained from PEK Labs, Inc., of Palo Alto,California. A pair of bridge elements 17 and 18 are fixed on the housing10 and extend across the open portion of the cavity 12. Each bridgeelement supports an insulator block 19 by means of a threaded 'fastening20. Each insulator block, in turn, supports a lamp socket 23 by means ofa resilient metallic connector 22. These connectors 22 can be spreadapart sufficiently to permit insertion of the lamp terminals 16 into thesockets 23. The threaded elements 25 serve to establish electricalcontact between the electrical lead wires 26 and the lamp terminals 16.

The transparent envelope of the lamp 14 is preferably positionedsymmetrically between the bridge elements 17 and 18, so that the majorportion of light emitted by the lamp 14 passes out of the cavity 12between the bridge elements 17 and 18, and the latter may beproportioned and shaped for assembly with respect to a motion-pictureprinter device, not shown. It is desirable to 3,265,885 7 PatentedAugust 9, 1966 coat the reflector surface 13 in the vicinity of the lampenvelope 15 with dichroic material in the manner disclosed in theStrawick Patent No. 3,099,403, in order that most of the visible lightspectrum be reflected 'while most of the invisible radiant energy andheat be transmitted into the material of the housing 10. One or moreaxial grooves 28 are provide-d in the reflecting surface 13 at the baseof the cavity 12 in order to minimize reflection of radiant energy backinto the transparent envelope 15.

Means are provided for cooling the lamp housing 10 and for cooling thelamp terminal 16, and as shown in the drawings this means includes anair chamber30 formed in the housing 10 and connected by a row of lateralports 31 and 32 to the cavity 12. The ports 31 are larger than theothers and are directed to cause jets of air or other gaseous coolant toflow from the chamber 30 against the joints 33 between the transparentenvelope 15 and the metallic terminal 16. The other ports 32 aredirected to cause jets of gaseous fluid to flow from the chamber 30against the transparent envelope itself. A

supply pipe (not shown) for air or other gaseous coolant is connected tothe chamber 30 by means of the threaded connector element 34. A fan (notshown) is provided for directing a blast of air axially along the outersurface of the housing 10 along the cooling fins 11 to extract heat asrapidly as possible from the housing 10. The bracket 35 is used formounting the housing 10 on the motionpicture printer device, not shown.

In the modified form of my invention shown in FIG- URE 4, annularcooling rings 40 are provided for, directing air other than gaseouscoolant against the transparent envelope 15 of the high-intensity lamp14, as well as against the metal terminal 16 and joints 33. The coolingrings 40 are threaded into the housing 1011 by means of hollow threadedelements 41 which connect the chamber 30a to the interior of each of thecooling rings 40. The cooling rings 40 are substantially aligned withthe bridge elements 17 and 18.

Having fully described my invention, it is to be understood that I amnot to be limited to the details herein set forth but that my inventionis of the full scope of the appended claims.

What is claimed is:

1. For use with a high intensity electric lamp having a cylindricaltransparent envelope positioned between axial ly extending metallicterminals, a lamp housing assembly having in combination: a housingprovided with an axial extending cavity for reception of the electriclamp, the cavity having walls defining a reflector surface, saidreflector surface having a dichroic coating at least in the regionadjacent the electric lamp, means including sockets for engaging thelamp terminals and establishing electrical connection to them, theelectric lamp being supported by said sockets axially of said cavity,the housing having at least one axial groove positioned symmetrically ofsaid reflector surface for minimizing reflection back into said electriclamp, the housing having a chamber therein,

- means for delivering a gaseous coolant into said chamber,

and means connected to said chamber for directing coolant against saidelectric lamp.

2. A lamp housing assembly for high intensity electric lamps of the typehaving a cylindrical transparent envelope positioned between coaxiallydisposed metallic terminals, said lamp housing assembly comprising: ahousing block for-med of metal having high heat conductivity anddefining a cavity of essentially parabolic cross section and having afocal axis extending the length of the housing block, said housing blockhaving a plurality of integral cooling fins extending from oppositesides thereof; means for supporting said electric lam-p by its terminalsat the focal axis of said cavity; a dichroic coating on at least i'ntosaid housing block'fo'r conduction to said cooling fins;

and means for passage of a cooling fluid including a passage formed insaid housing'block parallel to the focal axis of said housing, andorifices communicating with said passage and directed toward said lamp.3. A lamp housing according to claim 2, wherein said orifices arearranged in a row defining a plane passing through the focal axis ofsaid cavity. 4. A lamp housing according to claim 2 wherein a pair oftubular rings communicating with said passage-surround the terminals ofsaid electric lamp and said orifices are formed in said rings and aredirected radially inwardly toward said electric lamp. Y 5. A lamphousing assembly for high intensity electric lamps of the type having acylindrical transparent envelope positioned between coaxially disposedmetallic terminals, said lam-p housing assembly comprising: a housingblock formed of inetal having high heat conductivity and defining acavity of essentially parabolic cross section and having a focal axisextending thelength of the housing block, saidhousing block having aplurality of integral cooling fins extending from opposite sidesthereof, a pair of parallel plates bridged between opposite walls ofsaid cavity outwardly from the focal axis thereof, connectors supportedfrom said plates'extending toward said focal axis to support saidelectric .lamp by its terminals at said focal axis, a dichroic coatingon at least selected portions of the surface of said cavity for transferof radiant energy, principally in an invisible spectrum, into saidhousing for conduction to said cooling fins; and means for passage of acooling fluid including a passage formed in said housing block parallelto the focal axis of said housing, and orifices communicating with saidpassage and directed toward said lamp.

References Cited by the Examiner UNITED STATES PATENTS 2,006,402 7/1935Maxson 24o' 47 2,907,870 10/1959 Calmes 240-47 X 3,099,403 7/1963'Strawich 1 240 47 3,157,775 11/1964 Harmon-u, 24047X ANSHER, Primary C.R. RHODES, Assistant Examiner. I

2. A LAMP HOUSING ASSEMBLY FOR HIGH INTENSITY ELECTRIC LAMPS OF THE TYPEHAVING A CYLINDRICAL TRANSPARENT ENVELOPE POSITIONED BETWEEN COAXIALLYDISPOSED METALLIC TERMINALS, SAID LAMP ASSEMBLY COMPRISING: A HOUSINGBLOCK FORMED OF METAL HAVING HIGH HEAT CONDUCTIVITY AND DEFINING ACAVITY OF ESSENTIALLY PARABOLIC CROSS SECTION AND HAVING A FOCAL AXISEXTENDING THE LENGTH OF THE HOUSING BLOCK, SAID HOUSING BLOCK HAVING APLURALITY OF INTEGRAL COOLING FINS EXTENDING FROM OPPOSITE SIDESTHEREOF; MEANS FOR SUPPORTING SAID ELECTRIC LAMP BY ITS TERMINALS AT THEFOCAL AXIS OF SAID CAVITY; A DICHROIC COATING ON AT LEAST